title: Letrozole stimulation in endometrial preparation for cryopreserved-thawed embryo transfer in women with polycystic ovarian syndrome: a pilot study.
abstract: OBJECTIVE
  To study the efficiency of letrozole, an aromatase inhibitor, in endometrial preparation for cryopreserved-thawed embryo transfer (FET) in women with polycystic ovarian syndrome (PCOS).
  
  
  METHODS
  Retrospective observational study.
  
  
  METHODS
  One hundred and twenty patients with PCOS who met the inclusion criteria for the study.
  
  
  METHODS
  We assessed in vitro fertilization outcomes in one hundred and twenty patients with PCOS (148 cycles) who were prepared for and underwent FET between June 2011 and December 2012. Patients were prepared for FET using artificial hormone cycles induced with oestrogen and progesterone supplementation (n = 76), letrozole stimulation (n = 40) or hMG stimulation (n = 32).
  
  
  RESULTS
  There were no differences in demographic characteristics between the groups, except that the letrozole group had a higher incidence of embryo transfer failure in the past. The letrozole stimulation group had a significantly higher maximal endometrial thickness and significantly higher rates of clinical pregnancy per transfer, ongoing pregnancy per transfer and implantation, compared with the artificial and hMG stimulation groups. Differences in these parameters between the artificial and hMG stimulation groups were not significant.
  
  
  CONCLUSIONS
  Using letrozole stimulation in endometrial preparation for cryopreserved-thawed embryo transfer in patients with PCOS may be associated with better outcomes than using hormonal manipulation or hMG stimulation.
authors.affiliation: Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Yan-Jun
authors.initials: YJ
authors.lastname: Hu
authors.forename: Yue-Zhou
authors.initials: YZ
authors.lastname: Chen
authors.forename: Yi-Min
authors.initials: YM
authors.lastname: Zhu
authors.forename: He-Feng
authors.initials: HF
authors.lastname: Huang
mesh_terms: D000328:Adult; D047072:Aromatase Inhibitors / Q000627:therapeutic use; D015925:Cryopreservation; D004624:Embryo Transfer / Q000379:methods*; D004717:Endometrium / Q000187:drug effects* / Q000503:physiopathology; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D000077289:Letrozole; D008297:Male; D009570:Nitriles / Q000627:therapeutic use*; D010865:Pilot Projects; D011085:Polycystic Ovary Syndrome / Q000503:physiopathology*; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D014230:Triazoles / Q000627:therapeutic use*
chemical_list: D047072:Aromatase Inhibitors; D009570:Nitriles; D014230:Triazoles; D000077289:Letrozole